GMO foods are safe to eat, but they pose challenges in the environment.

Many aspects of modern technology make people a bit uneasy, but genetically modified foods may be in a class by themselves. Labs all around the world make genetic modifications of organisms—bacteria, plants, and animals—365 days a year. And some of the results of that work have been ingested by humans for years, often in the form of life-saving drugs. But genetically modified crops remain controversial around the globe, and while they're commonly used in the US, they have almost no presence in the European market.

The worries about GMO foods largely focus on their safety, but much of the debate ignores the extensive studies that have been done to understand both the potential risks and what we've learned about them. In response to this perceived gap in understanding, a group of Italian scientists have now performed a comprehensive review of the scientific literature on GMO crops (we were made aware of the review by Real Clear Science). The results suggest that GMO crops are safe for us, but there are some remaining concerns about their environmental impact that need to be nailed down. In the meantime, the authors suggest that GMOs represent a serious challenge for science communication with the public.

To get a grip on current research, the authors searched databases for any papers on the topic that were published between 2002 and October of 2012; they came up with 1,783 of them. But not all of these spoke directly to safety. The authors note that many of the articles published on GMO crops were commentaries, and the ones that directly addressed safety concerns tended to end up in low-profile publications. Confusing matters further, there were several areas of largely unrelated research that all speak to the safety of these crops.

What you ingest

There's one obvious concern when it comes to GMO crops: we eat them. Are we ingesting anything unusual? To understand that, you have to know how transgenic plants work. They start with a piece of DNA, one that carries a gene of interest—say, one that encodes a protein that provides the plant disease or pest resistance. That DNA is packaged with additional sequences that make sure the gene can be made by plant cells, along with a gene for drug resistance that lets you track whether the DNA is present in cells. The whole package is then inserted into one of the plant's chromosomes.

Once in a plant cell, the gene gets transcribed into RNA. In some cases, that's the end of it; the RNA is active in some way that's useful (for example, it might target a virus for destruction). But in many cases, that RNA is converted into protein, such as the Bt protein that is toxic to insect pests. In a few rare cases, that protein may catalyze the production of a specific chemical. One example of the latter is golden rice, which has been engineered to carry the genes needed to produce vitamin A.

So DNA, RNA, proteins, and chemicals. That's a lot to worry about, right?

Well, maybe not. Everyone's meals normally contain some DNA, but the average person only ingests between 0.1 and 1 gram of it every day. Most of that is the DNA that all plants and animals naturally contain; estimates are that the engineered DNA accounts for less than 0.00006 percent of the total. Cooking destroys most of it, and the majority of the rest is degraded in the harsh digestive environment.

There's a small chance that some of it will survive long enough to be taken up by gut bacteria, but this is a very uncommon event (otherwise your average E. coli would have a genome swimming with corn and cow DNA). The one potential risk there is that the bacteria will pick up the drug resistance gene that's part of the initial package inserted into the plant, but that poses little risk since biologists use resistance genes that are already widespread in bacterial populations, meaning the drugs aren't used much clinically.

Similar things apply to the RNA and proteins, in that most are fully digested long before they reach the bloodstream. (In fact, the review notes that this is precisely why we have to rely on injections to get protein- and RNA-based therapies into people.) There's been a single report that plant RNA may appear in the bloodstream of mice, but the results haven't been replicated since.

Another risk is that the proteins made by the GMO plant (or some digested fragment of it) will cause an allergic reaction. For that reason, the protein sequences are tested against a large database of common allergens. The proteins are also assessed for toxicity in animals and for their ability to survive a digestive environment. As far as any chemical end products are concerned, they're generally being used precisely because the chemical in question will have a beneficial effect on humans. Because all these risks from DNA, proteins, and chemicals are identical to those posed by unmodified plants, the European Commission has concluded that "the use of biotechnology and of GE plants per se does not imply higher risks than classical breeding methods or production technologies."

The only residual uncertainty is whether the mere presence of the RNA and proteins made by the transgenic DNA alters the plants in a systematic way. In a general sense, they don't; transgenic plants pass what's called a "substantial equivalence" test, which means they are indistinguishable from the crop that they were derived from in terms of nutrients and other key components.

However, if you do a detailed analysis of every protein and chemical produced by the plants (a proteomics and metabolomics study), you can see differences between the transgenics and other crops. But similar things happen if you raise identical crops in slightly different environments, so it's not clear if this is a real result or an experimental glitch—and, if it's the former, whether that tells us anything significant. The review's authors argue that this is an area that deserves further study.

GMOs and the environment

Although it's almost impossible for the genes to spread to humans, that doesn't mean they can't spread. Crops are grown in uncontrolled environments, where they come in contact with other species, some of which can be close relatives. For most species, this DNA doesn't provide any advantages that can't be provided by the DNA that's already present in the environment. Bacteria and insects won't benefit from picking up genes for herbicide resistance or insect-killing proteins. The drug resistance could benefit the bacteria, except the genes in use are already widespread in soil communities. And at least so far, field studies haven't found any evidence of transgenes ending up in soil bacteria.

The same cannot be said for plants, or at least those plants that are closely related to crops. There have been reports of a strain of canola that contains multiple herbicide resistance genes, which presumably came about through the hybridizing of two or more GM strains. Obviously, the transgene would provide a survival advantage for any plant that was growing near agricultural areas. The same would be true for the spread of genes that encode proteins that are toxic to insects, except the latter would provide a survival advantage just about anywhere.

These genes could also cause problems for agriculture itself. Currently, resistance to insecticidal proteins like Bt is limited in part by careful crop management. If wild plants pick up the same gene, it could hasten the evolution of resistant insects regardless of how the crops are managed. Although there are some ideas about how to limit the spread, there are problems with all of them: "none of them can be considered completely effective for transgene containment and complete segregation of GE [genetically engineered] crops is not possible."

Communication breakdown

The conclusion of the review is that from the perspective of human consumption, all evidence indicates that GMO foods are safe; the primary risks are to agriculture itself, primarily from the unintended spread of some of the transgenes to wild populations.

But that's hardly the impression you'd get from the public debate. GM foods are often portrayed as untested or their safety a complete unknown. Rare, unreproducible results are often trumpeted as the final word. These are features that are shared with a number of other areas where there's been a failure of science communication, and the authors argue that scientists themselves share the blame here: "the frequent non-scientific disputes in the media that are not balanced by an effective communication from the scientific and academic world, greatly contribute to enhance the concerns on GE crops."

But the review points out that effective communication is hard because the scientific community is never 100 percent unified. The authors note that there is "animated debate regarding the suitability of the experimental designs, the choice of the statistical methods, or the public accessibility of data," and that's all a healthy sign that science is following its normal course here, even as its conclusions firm up. Unfortunately, this healthy debate has "frequently been distorted by the media and often used politically and inappropriately in anti-GE crops campaigns."

All of which makes getting the big picture—GM foods appear safe to eat—a difficult message to elevate above the noise.

335 Reader Comments

That's cool and all, but I'll still choose not to consume them and demand their labeling. I'm all for science, but even so, it's not like money can't be used to ensure that experiments produce the desired results...and the companies making GMO foods have a LOT of money.

The one potential risk there is that the bacteria will pick up the drug resistance gene that's part of the initial package inserted into the plant, but that poses little risk since biologists use resistance genes that are already widespread in bacterial populations, meaning the drugs aren't used much clinically.

That's cool and all, but I'll still choose not to consume them and demand their labeling. I'm all for science, but even so, it's not like money can't be used to ensure that experiments produce the desired results...and the companies making GMO foods have a LOT of money.

Labeling specific kinds of GMO that might have an expectation to be harmful would make sense, but they wouldn't be allowed into the food supply. Labeling all GMO products as generically GMO is in all respects meaningless.

This wasn't mentioned above, but the dangers of monocultures should probably be included with "agricultural concerns". Whenever we start using GMO crops, we reduce significantly the variety of plants that we grow. When certain bacteria or environmental conditions change there's a serious danger of widespread famine. Something that native varieties generally resist much better.

While including GMO labels for medical reasons may be non-sensical, it could make more sense from an ideological perspective.

Labeling specific kinds of GMO that might have an expectation to be harmful would make sense, but they wouldn't be allowed into the food supply. Labeling all GMO products as generically GMO is in all respects meaningless.

If part of the process is testing on animals and I was the type of person to not support that, then yes it should all be labelled.

1.) Even if they may be safe to eat... The effect on the environment should have a much higher priority here.2.) And far more important: As long as genetically 'enhanced' food is abused by big companies in more or less monopol position to squeeze the last buck out of farmers, it simply is a no-go. The advantage of traditional selection and breeding especially with plants is, it relies on fertile seeds, which farmers can stache to use next season. The big companies try to make this practice illegal. European farmers don't want to be at the mercy of some big US-seed company. It is as simple as that. As long as they stick to the practice of patenting the stuff they produce and thus criminalize simple farmers keeping their stache for the next season, we DONT want them.

The GMO debate is one that is loaded with misinformation. It's extremely difficult to find reliable information on the subject. I appreciate this article for that.

One of the concerns about GMOs seems to be that they are built to be pesticide resistant so that farmers can just lace their fields with Monsanto's own Round Up. Then the pesticides end up showing up in the food -- allegedly. I don't see that mentioned in this article, and finding reliable information on the subject is an exercise in futility.

The other concern is that Monsanto is a pretty slimy company. Their seeds don't produce plants that create more seeds, so farmers always have to buy high priced seeds from the company every season. That just seems unethical to me, but "it's just business" right?

Organic farming isn't always pesticide free either. They use some pretty nasty natural chemicals like strychnine in some instances. And organic farming cannot produce enough food for our entire population. GMOs can definitely be a good thing.

EDIT: RoundUp is actually a weed killer, but the point is still the same.

The biggest "risk" with GMOs resides in its intellectual property. I would worry a little less about GMOs if it was not private science, enforced by industrial justice systems.

As for the environment, mankind has already messed it up so badly that one more heavy-handed divine intervention in food chains and ecosystems won't change the outcome. The game changer here is the market control and universal availability.

That's cool and all, but I'll still choose not to consume them and demand their labeling. I'm all for science, but even so, it's not like money can't be used to ensure that experiments produce the desired results...and the companies making GMO foods have a LOT of money.

We just need better labeling in general. Do some investigation into the variety of "natural flavors" out there. Beaver anal gland extract is included in those natural flavors.

What bothers me more is the possibility of a sort of monoculture effect. Those lovely sweet yellow bananas we're used to are vulnerable due to lack of genetic diversity... a disease could run rampant faster than breeding or even GMO could address it. If a benevolent gene applied to multiple organisms also turns out to also be an attack vector for a disease, then several crops could "go down" at once.

The other concern is that Monsanto is a pretty slimy company. Their seeds don't produce plants that create more seeds, so farmers always have to buy high priced seeds from the company every season. That just seems unethical to me, but "it's just business" right?

You seem to be under the impression that Monsanto is using so-called "terminator" seed technology, where the plants grown from purchased seeds are sterile, and produce no seeds of their own. You're mistaken - check it out for yourself. Monsanto *does*, on the other hand, include contractual language in their purchase agreements saying that farmers can't just grow one season's worth of crops and use a portion from that crop to seed the next year, and so on. Some commenters seem to think that seed purchase agreements have only been around starting with Monsanto and GMO crops, but that's not true.

I support labeling simply because it allows people to make an informed choice. Maybe the non-GMO food will, like organic food, be more expensive. But those that can afford to pay for that should be able to make that decision without having to guess. Like organic food, there is a marketplace there, and appealing to it isn't a bad thing.

Personally, my fear, rational or not, has to do with increased reports of gluten allergies. Now this could be attributable to many things, but nature is complex enough that mucking about with the genes seems potentially dangerous. Studies like this, where rats fed GMOs had increased likelihood of death and tumors, worry me, not because I necessarily understand why such effects might be, but specifically because I don't understand.

Now, I'm willing to be educated, so don't take my position as absolute. Right now, I have an uncertainty, and that uncertainty makes me have a preference for what has been safe in the past. I am fortunate enough to have the means to pay for non-GMO food, the finding of which can be difficult.

Long story short, I worry about GMOs because I think the testing process for them is far too short. I'm all for pushing science, but I'm not for using the population as a whole as a test subject. I'm sure the anti-GMO fervor is a combination of fact, fiction, and international politics. For myself though, I'll want more testing done on a longer term to determine safety.

Here's a great article written by a guy who once tore GM crops up in protest, and who is now trying to make amends. His message is that an evidence-based approach not only shows GMO to be safe to eat, but also that it's becoming necessary to mankind to sustainably living on planet Earth. The irrational human response to GMO is actually hurting the environment and our future. Like all issues, the wisest approach is always science and evidence.

That's cool and all, but I'll still choose not to consume them and demand their labeling. I'm all for science, but even so, it's not like money can't be used to ensure that experiments produce the desired results...and the companies making GMO foods have a LOT of money.

How about you pay for that instead? Do you realize how much of your non-GMO food is subsidized by GMO food? The profit made by Monsanto et al pales in comparison to the economic benefit they've provided for people who eat food everywhere (read: everyone) and people who like to breathe (read: everyone).

If GMO food didn't exist there would either be a couple billion more people starving to death, or a lot less rainforest in the world. There's no way around the math that the only reason we can support 7 billion people and still have forests is with the increased yields made possible by GMO food.

Labeling specific kinds of GMO that might have an expectation to be harmful would make sense, but they wouldn't be allowed into the food supply. Labeling all GMO products as generically GMO is in all respects meaningless.

That's not necessarily so. Testing products against "common allergens" is all well and good, but if you have an uncommon allergen, you are basically S.O.L. -- without labeling you can't avoid the problem food. I have a personal and vested interest in that issue, having an uncommon but deadly allergy. It doesn't keep me up at night since no one is (yet) using that allergen in a GMO (that I know of), but that could easily change.

I think the problem with the GMO and the public is less about science education, although that's an issue, than it is about the actions of companies like Monsanto. It's very easy to paint them as an evil company, uncaring of the public consequences, who does bad things in the name of profit because frankly they DO. It's even more unfortunate when cases like that of Percy Schmeiser, who *knew* he was violating the seed license, get more publicity than other cases where the farmer is not at fault but suffers the Monsanto version of patent trolling.

The other concern is that Monsanto is a pretty slimy company. Their seeds don't produce plants that create more seeds, so farmers always have to buy high priced seeds from the company every season. That just seems unethical to me, but "it's just business" right?

You seem to be under the impression that Monsanto is using so-called "terminator" seed technology, where the plants grown from purchased seeds are sterile, and produce no seeds of their own. You're mistaken - check it out for yourself. Monsanto *does*, on the other hand, include contractual language in their purchase agreements saying that farmers can't just grow one season's worth of crops and use a portion from that crop to seed the next year, and so on. Some commenters seem to think that seed purchase agreements have only been around starting with Monsanto and GMO crops, but that's not true.

Sorry, there's no place for your facts in this discussion. You must be new to the internet.

The terminator seeds that Monsanto has developed - seeds that do not germinate for the next season - are my biggest concern personally. The end of the plant life cycle as we know it is essentially being perfected for no other reason than to increase their profit.

The other thing that is hard, I think, for the public to separate is pesticides from GMOs because most of the time it's the same companies producing both products, and there have been many studies and direct evidence that many pesticides cause serious side effects and are one of the primary reasons for colony collapse in bees that we have been witnessing for the past years.

The fact that GMOs are giving these corrupt companies more power is enough of a reason for me to avoid them right now.

I think some of the skepticism also comes from the question of who pays for these studies? Are they funded by the GMO manufacturers? And do those sponsors have any say (explicit or implicit through pulling future funding) as to whether reports get published based on the results? When you're dealing with some of these companies and their shady practices, it's not exactly a stretch.

The same cannot be said for plants, or at least those plants that are closely related to crops. There have been reports of a strain of canola that contains multiple herbicide resistance genes, which presumably came about through the hybridizing of two or more GM strains. Obviously, the transgene would provide a survival advantage for any plant that was growing near agricultural areas. The same would be true for the spread of genes that encode proteins that are toxic to insects, except the latter would provide a survival advantage just about anywhere.

I think this pretty much sums up why gene patents and Monsanto shouldn't have the power they have. It's impossible to not have these genes spread into the environment (including nonMonsanto fields).

1.) Even if they may be safe to eat... The effect on the environment should have a much higher priority here.2.) And far more important: As long as genetically 'enhanced' food is abused by big companies in more or less monopol position to squeeze the last buck out of farmers, it simply is a no-go. The advantage of traditional selection and breeding especially with plants is, it relies on fertile seeds, which farmers can stache to use next season. The big companies try to make this practice illegal. European farmers don't want to be at the mercy of some big US-seed company. It is as simple as that. As long as they stick to the practice of patenting the stuff they produce and thus criminalize simple farmers keeping their stache for the next season, we DONT want them.

1) The "effect on the environment" is limited to less chemicals used in farming and the possibility of gene transfer to similar wild plants.

2) Farmers don't have use GM seeds. They use them, or don't, by choice. The demonizing GM is actually removing their choice in the mater.

This is one of those things where the risks of allergy/long-term repercussions are present, but GMO will eventually rank higher on the benefit/risk totem pole if we run out of alternatives. Right now, Australian soil is selenium depleted, meaning that foodstuff grown in that soil is selenium depleted, and Australians are at risk of selenium deficiencies. As the climate becomes more arid, this is likely to continue, and it is possible that we, a first-world country will have to turn to GMO out of necessity, just as third world countries are doing now with golden rice. But not a moment sooner than necessary, because Monsanto turned something potentially awesome into something a lot more sleazy.

I don't have a problem with GMO produce in general. Humans have been futzing with plant genes (through splicing plants together and selective breeding) for thousands of years. Now, we are just more selective, creative, and precise through improved tools.

The potential problem that I have is the reasoning why the plants are modified in the first place. Improving the nutrients of an indigenous plant to provide something that's missing, like golden rice, is a great thing, and I fully support it.

Making the plant pesticide/herbicide/insecticide resistant so that a field can be drown in the stuff, I'm completely against. First there's the issue of whether or not those -icides make it into the plant itself which is later ingested. Maybe it does, maybe it doesn't. Research seems to be inconclusive at this time. Second, is the workers in the fields are working in and around these chemicals day after day. This can, and does, have an impact on their health. Lastly, not all the chemicals sprayed make it onto the crops. Some goes onto the soil, and then into the ground water, where it can then make its way into the water system.

On the environmental side, three items which were not mentioned but are hot topics at the moment:

1) Monarchs

2) Round-up resistant amaranth

3) 2, 4-D

starting with the first two: the advancement of round-up-ready corn allows for much larger quantities of round-up herbicide to be sprayed on fields - the corn is designed to handle the herbicide without succumbing to it. The downside is that this has done a great job of killing off weeds, including milkweed which monarch butterflies rely on. This year is a record low year for monarchs, with commonly teeming areas completely empty. Weather helped, but round up played a large part. http://www.news-gazette.com/news/local/ ... ssing.html

Additionally, the larger amounts of round-up have led to selective pressures on the edges of the fields, where, in addition to cross-hybridizing, wild species (i.e. weeds) have begun developing their own resistance. Resistant amaranth, aka pigweed, is becoming a very large problem in the midwest because of this, and is only likely to get worse. http://www.uaex.edu/Other_Areas/publica ... A-2152.pdf

To fight this growing resistance, the testing of another herbicide and corn designed to withstand it in high doses - 2, 4D - is ongoing. In areas near the fields where this testing is occurring are showing early signs of being cancer hotspots (though possibly due to the dust itself RE: silicosis, rather than the herbicide. There is mixed evidence of 2,4-D being carcinogenic in humans, though it may cause Lou Gehrig's disease in higher doses) roundup itself can be carcinogenic, so larger qualities of either are potentially a health concern for workers and immediate neighbors). That said, the "agent orange corn" moniker is just fear mongering, and I dislike that as much as continuously attempting to fix problems with sledgehammers as we're doing.

But my baby was born austistics, and I did everything right! No, no, it's Monsanto that's to blame, not my genes or my baby's infrequent pre-natal exposure to alcohol and nicotine! Look at it, it isn't even vaccinated!

"the use of biotechnology and of GE plants per se does not imply higher risks than classical breeding methods or production technologies."

Classical breeding is worse, because in order to get the starting pairs to breed, the organisms are exposed to mutagens that trigger mutations to all of the DNA, not just adding/removing/changing single genes. Are there even any crops left that have only been come to without mutation caused by a person?

Not to say it's necessarily dangerous, but making one change seems safer than messing with the whole thing.

The terminator seeds that Monsanto has developed - seeds that do not germinate for the next season - are my biggest concern personally. The end of the plant life cycle as we know it is essentially being perfected for no other reason than to increase their profit.

Initially developed as a concept by the United States Department of Agriculture and multinational seed companies, Terminator seeds have not been commercialized anywhere in the world due to opposition from farmers, indigenous peoples, NGOs, and some governments. In 2000, the United Nations Convention on Biological Diversity recommended a de facto moratorium on field-testing and commercial sale of terminator seeds; the moratorium was re-affirmed in 2006. India and Brazil have passed national laws to prohibit the technology.[2]

Fact: Monsanto has never commercialized a biotech trait that resulted in sterile – or “Terminator” – seeds. Sharing the concerns of small landholder farmers, Monsanto made a commitment in 1999 not to commercialize sterile seed technology in food crops. We stand firmly by this commitment, with no plans or research that would violate this commitment.

What history tells us is that all human activity involves risk. The emergence of agriculture resulted in a very large scale transformation of the Earth's inhabitants. All the consequences of that transformation are still not understood. Genetic modification of food crops is just one step in that process. Science can give us some confidence that the risks in that step are containable. But, there is no way of knowing exactly what all those risks are.Clearly one consequence of the discovery of agriculture and of industrialization has been a very large human population on Earth. That population is not likely to be sustainable without taking the risks that are required for human beings to have better control over our food sources and the environment of the Earth. On the scale of the required risks, those involved in genetically engineering food sources are likely to prove relatively modest.